<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>主页</title>
</head>
<body>
    <header>
        <h1>您好，请问需要什么服务</h1>
    </header>
    <div>
        {% block content_a %}{% endblock %}
    </div>
</body>
</html>
